System and method for imaging a subject

ABSTRACT

A method and system is disclosed for acquiring image data of a subject. The image data can be collected with an imaging system in a selected manner and/or motion. More than one projection may be combined to generate and create a selected view of the subject.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application includes subject matter similar to that disclosed inU.S. application Ser. No. 16/233,855 filed on Dec. 27, 2018. The entiredisclosures of each of the above applications are incorporated herein byreference.

FIELD

The present disclosure relates to imaging a subject, and particularly toa system to acquire image data for generating a selected view of thesubject.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

A subject, such as a human patient, may undergo a procedure. Theprocedure may include a surgical procedure to correct or augment ananatomy of the subject. The augmentation of the anatomy can includevarious procedures, such as movement or augmentation of bone, insertionof an implant (i.e. an implantable device), or other appropriateprocedures.

A surgeon can perform the procedure on the subject with images of thesubject that are based on projections of the subject. The images may begenerated with imaging systems such as a magnetic resonance imaging(MRI) system, computed tomography (CT) system, fluoroscopy (e.g. C-Armimaging systems), or other appropriate imaging systems.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

According to various embodiments, a system to acquire image data of asubject with an imaging system may use x-rays. The subject may be aliving patient (e.g. a human patient). The subject may also be anon-living subject, such as an enclosure, a casing, etc. The imagingsystem may include a moveable source and/or detector that is moveablerelative to the subject.

An imaging system may include a movable source and/or detector to createa plurality of projections of a subject. The plurality of projectionsmay be acquired in a linear path of movement of the source and/ordetector. The plurality of projections may then be combined, such as bystitching together, to generate or form a long view (also referred to asa long film). The long view may be a two-dimensional view of thesubject.

In various embodiments, the imaging system may acquire a plurality ofprojections at different perspectives relative to the subject. Thedifferent perspectives may be generated due to a parallax effect betweendifferent paths of x-rays from a single source to the detector throughthe subject. The parallax effect may allow for different views of thesame position of the subject. The parallax effect may be formed due to afilter having a plurality of slits or slots through which the x-rayspass and impinge upon the detector. Accordingly, movement of the sourceand/or detector relative to the subject may allow for acquisition of aplurality of projections through the subject including a parallaxeffect. The plurality of projections may then be stitched to form aplurality of long views of the subject due to movement of the sourceand/or detector.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is an environmental view of an imaging system in an operatingtheatre;

FIG. 2 is a detailed schematic view of an imaging system with a dualenergy source system;

FIG. 3 is a perspective view of a filter assembly, according to variousembodiments;

FIG. 4A is an exploded view of a slot filter assembly, according tovarious embodiments;

FIG. 4B is a top plan view of a slot filter body, according to variousembodiments;

FIG. 4C is a cross-sectional view of a slot filter body that's aboutline 4C of FIG. 4B;

FIG. 5A and FIG. 5B are schematic illustrations of a slot filterassembly relative to a source and detector;

FIG. 6 is a flow chart performing a long view or long film image,according to various embodiments;

FIG. 7 is a detailed flow chart of a portion of the long view method;

FIG. 8 is a schematic illustration of acquiring a plurality ofprojections in intermediate images, according to various embodiments;

FIG. 9A is a schematic illustration of a focus plane relative to a slotfilter assembly;

FIG. 9B is a schematic illustration of a registration of intermediateimages;

FIG. 10 is a schematic illustration of a formation of a long view with aweighting function; and

FIG. 11 is a gaussian graph of an intensity plot relative to a detectorwith a fan x-ray.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With reference to FIG. 1, a schematic view of a procedure room 20 isillustrated. A user 24, such as a surgeon, can perform a procedure on asubject, such as a patient 28. The subject may be placed on a support,such as a table 32 for a selected portion of the procedure. The table 32may not interfere with image data acquisition with an imaging system 36.In performing the procedure, the user 12 can use the imaging system 36to acquire image data of the patient 28 to allow a selected system togenerate or create images to assist in performing a procedure. Imagesgenerated with the image data, such as a model (such as athree-dimensional (3D) image), long views, single projections views,etc. can be generated using the image data and displayed as an image 40on a display device 44. The display device 44 can be part of and/orconnected to a processor system 48 that includes an input device 52,such as a keyboard, and a processor 56, which can include one or moreprocessors or microprocessors incorporated with the processing system 48along with selected types of non-transitory and/or transitory memory 58.A connection 62 can be provided between the processor 56 and the displaydevice 44 for data communication to allow driving the display device 44to display or illustrate the image 40. The processor 56 may be anyappropriate type of processor such as a general purpose processor thatexecutes instructions included in a program or an application specificprocessor such as an application specific integrated circuit.

The imaging system 36 can include an O-Arm® imaging system sold byMedtronic Navigation, Inc. having a place of business in Louisville,Colo., USA. The imaging system 36, including the O-Arm® imaging system,or other appropriate imaging systems may be in use during a selectedprocedure, such as the imaging system described in U.S. Patent App.Pubs. 2012/0250822, 2012/0099772, and 2010/0290690, all incorporatedherein by reference.

The imaging system 36, when, for example, including the O-Arm® imagingsystem, may include a mobile cart 60 that includes a controller and/orcontrol system 64. The control system 64 may include a processor and/orprocessor system 66 (similar to the processor 56) and a memory 68 (e.g.a non-transitory memory). The memory 68 may include various instructionsthat are executed by the processor 66 to control the imaging system 36,including various portions of the imaging system 36.

The imaging system 36 may include further addition portions, such as animaging gantry 70 in which is positioned a source unit (also referred toas an assembly) 74 and a detector unit (also referred to as an assembly)78. The gantry 70 is moveably connected to the mobile cart 60. Thegantry 70 may be 0-shaped or toroid shaped, wherein the gantry 70 issubstantially annular and includes walls that form a volume in which thesource unit 74 and detector 78 may move. The mobile cart 60 may also bemoved, and can be moved from one operating theater to another and oranother room. The gantry 70 can move relative to the cart 60, asdiscussed further herein. This allows the imaging system 36 to be mobileand moveable relative to the subject 28 thus allowing it to be used inmultiple locations and with multiple procedures without requiring acapital expenditure or space dedicated to a fixed imaging system.

The processor 66 may be a general purpose processor or a specificapplication processor. The memory system 68 may be a non-transitorymemory such as a spinning disk or solid state non-volatile memory. Invarious embodiments, the memory system may include instructions to beexecuted by the processor 66 to perform functions and determine results,as discussed herein.

In various embodiments, the imaging system 36 may include an imagingsystem that acquires images and/or image data by the use of emittingx-rays and detecting interactions and/or attenuations of the x-rays withthe subject 28. Thus, x-ray imaging may be an imaging modality. It isunderstood that other imaging modalities are possible.

Thus, the imaging system 36 that includes the source unit 74 may be anx-ray emitter that can emit x-rays through the patient 28 to be detectedby the detector 78. As is understood by one skilled in the art, thex-rays emitted by the source 74 can be emitted in a cone 90 along aselected main vector 94 and detected by the detector 78, as illustratedin FIG. 2. The source 74 and the detector 78 may also be referred totogether as a source/detector unit 98, especially wherein the source 74is generally diametrically opposed (e.g. 180 degrees apart) from thedetector 78 within the gantry 70.

The imaging system 36 may move, as a whole or in part, relative to thesubject 28. For example, the source 74 and the detector 78 can move in a360° motion around the patient 28. The movement of the source/detectorunit 98 within the gantry 70 may allow the source 74 to remain generally180° opposed (such as with a fixed inner gantry or rotor or movingsystem) to the detector 78. Thus, the detector 78 may be referred to asmoving around (e.g. in a circle or spiral) the subject 28 and it isunderstood that the source 74 is remaining opposed thereto, unlessdisclosed otherwise.

Also, the gantry 70 can move isometrically (also referred as “wag”relative to the subject 28 generally in the direction of arrow 100around an axis 102, such as through the cart 60, as illustrated inFIG. 1. The gantry 34 can also tilt relative to a long axis 106 of thepatient 28 illustrated by arrows 110. In tilting, a plane of the gantry70 may tilt or form a non-orthogonal angle with the axis 106 of thesubject 28.

The gantry 70 may also move longitudinally in the direction of arrows114 along the line 106 relative to the subject 28 and/or the cart 60.Also, the cart 60 may move to move the gantry 70. Further, the gantry 70can move up and down generally in the direction of arrows 118 relativeto the cart 30 and/or the subject 28, generally transverse to the axis106 and parallel with the axis 102.

The movement of the imaging system 60, in whole or in part is to allowfor positioning of the source/detector unit (SDU) 98 relative to thesubject 28. The imaging device 36 can be precisely controlled to movethe SDU 98 relative to the subject 28 to generate precise image data ofthe subject 28. The imaging device 36 can be connected with theprocessor 56 via a connection 120, which can include a wired or wirelessconnection or physical media transfer from the imaging system 36 to theprocessor 56. Thus, image data collected with the imaging system 36 canbe transferred to the processing system 56 for navigation, display,reconstruction, etc.

The source 74, as discussed herein, may include one or more sources ofx-rays for imaging the subject 28. In various embodiments, the source 74may include a single source that may be powered by more than one powersource to generate and/or emit x-rays at different energycharacteristics. Further, more than one x-ray source may be the source74 that may be powered to emit x-rays with differing energycharacteristics at selected times.

According to various embodiments, the imaging system 36 can be used withan un-navigated or navigated procedure. In a navigated procedure, alocalizer and/or digitizer, including either or both of an opticallocalizer 130 and/or an electromagnetic localizer 138 can be used togenerate a field and/or receive and/or send a signal within a navigationdomain relative to the subject 28. The navigated space or navigationaldomain relative to the subject 28 can be registered to the image 40.Correlation, as understood in the art, is to allow registration of anavigation space defined within the navigational domain and an imagespace defined by the image 40. A patient tracker or dynamic referenceframe 140 can be connected to the subject 28 to allow for a dynamicregistration and maintenance of registration of the subject 28 to theimage 40.

The patient tracking device or dynamic registration device 140 and aninstrument 144 can then be tracked relative to the subject 28 to allowfor a navigated procedure. The instrument 144 can include a trackingdevice, such as an optical tracking device 148 and/or an electromagnetictracking device 152 to allow for tracking of the instrument 144 witheither or both of the optical localizer 130 or the electromagneticlocalizer 138. A navigation/probe interface device 158 may havecommunications (e.g. wired or wireless) with the instrument 144 (e.g.via a communication line 156), with the electromagnetic localizer 138(e.g. via a communication line 162), and/or the optical localizer 60(e.g. via a communication line 166). The interface 158 can alsocommunicate with the processor 56 with a communication line 168 and maycommunicate information (e.g. signals) regarding the various itemsconnected to the interface 158. It will be understood that any of thecommunication lines can be wired, wireless, physical media transmissionor movement, or any other appropriate communication. Nevertheless, theappropriate communication systems can be provided with the respectivelocalizers to allow for tracking of the instrument 144 relative to thesubject 28 to allow for illustration of a tracked location of theinstrument 144 relative to the image 40 for performing a procedure.

One skilled in the art will understand that the instrument 144 may beany appropriate instrument, such as a ventricular or vascular stent,spinal implant, neurological stent or stimulator, ablation device, orthe like. The instrument 144 can be an interventional instrument or caninclude or be an implantable device. Tracking the instrument 144 allowsfor viewing a location (including x,y,z position and orientation) of theinstrument 144 relative to the subject 28 with use of the registeredimage 40 without direct viewing of the instrument 144 within the subject28.

Further, the imaging system 36, such as the gantry 70, can include anoptical tracking device 174 and/or an electromagnetic tracking device178 to be tracked with the respective optical localizer 130 and/orelectromagnetic localizer 138. Accordingly, the imaging device 36 can betracked relative to the subject 28 as can the instrument 144 to allowfor initial registration, automatic registration, or continuedregistration of the subject 28 relative to the image 40. Registrationand navigated procedures are discussed in the above incorporated U.S.Pat. No. 8,238,631, incorporated herein by reference. Upon registrationand tracking of the instrument 144, an icon 180 may be displayedrelative to, including overlaid on, the image 40.

With continuing reference to FIG. 2, according to various embodiments,the source 74 can include a single x-ray tube assembly 190 that can beconnected to a switch 194 that can interconnect a first power source 198via a connection or power line 200. As discussed above, X-rays can beemitted from the x-ray tube 190 generally in the cone shape 90 towardsthe detector 78 and generally in the direction from the x-ray tube 190as indicated by arrow, beam arrow, beam or vector 94. The switch 194 canswitch power on or off to the tube 190 to emit x-rays of selectedcharacteristics, as is understood by one skilled in the art. The vector94 may be a central vector or ray within the cone 90 of x-rays. An x-raybeam may be emitted as the cone 90 or other appropriate geometry. Thevector 94 may include a selected line or axis relevant for furtherinteraction with the beam, such as with a filter member, as discussedfurther herein.

The subject 28 can be positioned within the x-ray cone 94 to allow foracquiring image data of the subject 28 based upon the emission of x-raysin the direction of vector 94 towards the detector 78.

The x-ray tube 190 may be used to generate two dimension (2D) x-rayprojections of the subject 28, including selected portions of thesubject 28, or any area, region or volume of interest, in light of thex-rays impinging upon or being detected on a 2D or flat panel detector,as the detector 78. The 2D x-ray projections can be reconstructed, asdiscussed herein, to generate and/or display three-dimensional (3D)volumetric models of the subject 28, selected portion of the subject 28,or any area, region or volume of interest. As discussed herein, the 2Dx-ray projections can be image data acquired with the imaging system 36,while the 3D volumetric models can be generated or model image data.

For reconstructing or forming the 3D volumetric image, appropriatealgebraic techniques include Expectation maximization (EM), OrderedSubsets EM (OS-EM), Simultaneous Algebraic Reconstruction Technique(SART) and Total Variation Minimization (TVM), as generally understoodby those skilled in the art. The application to perform a 3D volumetricreconstruction based on the 2D projections allows for efficient andcomplete volumetric reconstruction. Generally, an algebraic techniquecan include an iterative process to perform a reconstruction of thesubject 28 for display as the image 40. For example, a pure ortheoretical image data projection, such as those based on or generatedfrom an atlas or stylized model of a “theoretical” patient, can beiteratively changed until the theoretical projection images match theacquired 2D projection image data of the subject 28. Then, the stylizedmodel can be appropriately altered as the 3D volumetric reconstructionmodel of the acquired 2D projection image data of the selected subject28 and can be used in a surgical intervention, such as navigation,diagnosis, or planning. The theoretical model can be associated withtheoretical image data to construct the theoretical model. In this way,the model or the image data 40 can be built based upon image dataacquired of the subject 28 with the imaging device 36.

With continuing reference to FIG. 2, the source 74 may include variouselements or features that may be moved relative to the x-ray tube 190.In various embodiments, for example, a collimator 220 may be positionedrelative to the x-ray tube 190 to assist in forming the cone 90 relativeto the subject 28. The collimator 220 may include various features suchas movable members that may assist in positioning one or more filterswithin the cone 90 of the x-rays prior to reaching the subject 28.Further, as discussed further herein, various filters may be used toshape the x-ray beam, such as shaping the cone 90, into a selected shapeprior to reaching the subject 28. In various embodiments, as discussedherein, the x-rays may be formed into a thin fan or plane to reach andpass through the subject 28 and be detected by the detector 78.

Accordingly, the source 74 including the collimator 220 may include afilter assembly 224. The filter assembly 224 may include one or moreportions that allow for moving a filter relative to the x-ray tube 190to shape and/or position the x-rays prior to reaching the subject 28.For example, with reference to FIG. 3, the filter assembly 224 mayinclude a stage 228. The stage 228 may be positioned relative to thex-ray tube 190 and may substantially block all x-rays and/or define aninitiation of the cone 90 as the x-rays pass through a stage exposureopening 232. The stage opening 232 may be an opening or passage throughthe stage 228 that allows x-rays to exit the x-ray tube 190 and form thecone 90.

As illustrated in FIG. 3, a filter holding assembly 240 may include amovable filter holder or ladder 244. The filter ladder 244 may includeone or more filter holding positions such as a first open position 246,a first filter or solid filter member 250, and a third or slot filtermember 260, as discussed further herein. The filter ladder 244 may moveon one or more rails, such as a first rail 264 and a second rail 266.The filter ladder 244 may be connected with one or more carrier members,such as a ladder car including a first carrier 268 that moves along thefirst rail 264 and a second carrier member 270 that moves along thesecond rail 266. It is understood that opposite or opposing carriermembers may also be provided to ensure smoothness and/or selected planarmovement of the filter ladder 244, therefore including a third carrier274 and a fourth carrier 276. The third and fourth carriers 274, 276 mayride on the respective rails 264, 266 as the first and second carriers268, 270. Accordingly, the filter ladder 244 may generally move in thedirection of the double headed arrow 280 to selectively position theopen filter portion 246, the solid filter portion 250, or the slotfilter portion 260 relative to the aperture or passage opening 232 toallow x-rays to form the beam 90 or otherwise impinge on the subject 28,as discussed further herein. The filter assembly 224 may be used toaugment an emission of x-rays from the x-ray tube 190 to assist ingenerating an image or image data of the subject 28, as discussedfurther herein.

The filter carrier or filter ladder 244 may be moved by selectedmechanisms, such as servos or drive motors that are associated with therespective carriers 268, 270, 274, 276, or other appropriate mechanisms.Moving the filter ladder 244 may be controlled by the user 24, such asthrough manual input, and/or instructions provided to the imaging system26. For example, the control system 64 may execute selected instructionsto move the filter carrier 244 in a selected manner. Further, thecontrol system 64 may move the filter carrier 244 at a selected timebased upon selected inputs, such as inputs from the user 24, regardingselected images or image data to be acquired of the subject 28.Accordingly, the filter assembly 224 may be controlled by the controller64 and/or any other appropriate controller, such as the processor system48.

With reference to FIG. 4A, FIG. 4B, and FIG. 4C the slot filter assembly260 is illustrated in greater detail. The slot filter assembly 260 mayinclude a filter assembly that is formed of one or more members. It isunderstood, however, that the slot filter assembly may be formed of asingle member including only the slot filter body 352, as discussedfurther herein. In various embodiments, the slot filter assembly 260includes a slotted member or portion 300 that may be sandwiched betweenor placed between a first member or sheet 304 and a second member orsheet 308. It is understood, however, that the slotted member is notplaced between the first member 304 and the second member 308. The firstand second members 304, 308 may both be placed on a single side and/orincorporated into a single member placed on a single side of the slottedmember 300. In various embodiments, however, the first and secondmembers 304, 308 are solid and assist in ensure that slots 340, 344, 348(discussed further herein) remain free and clear of debris.

The first sheet 304 may be formed of a selected material, such assubstantially pure aluminum (i.e. pure aluminum as generally availableto one skilled in the art), aluminum alloy, or other appropriatealuminum material. The top member 304 may include a first or exteriorside 312 and a bottom or contact side 314. The two sides or surfaces312, 314 may be substantially planar. The bottom or second side 314 maycontact a first side 320 of the slotted member 300. The second side 314may be adhered to the first side 320, such as with a selected adhesiveor bonding member, such as an adhesive transfer tape. The thickness, ordistance between the first side 312 and the second side 314 may be about0.01 inches (in) to about 0.05 in, including about 0.02 in (about 0.5millimeters (mm)).

The second layer or member 308 may include a first surface 324 that maybe an exterior surface and a second surface or interior surface 326. Thesecond surface 326 may contact a bottom or second surface 330 of theslotted member 300. The second layer 308, however, may include or beformed as a dual material construction formed of an aluminum portion 309(formed of the same or similar aluminum materials as discussed above)and a copper portion 310 (e.g. substantially pure copper). In variousembodiments, the first portion may be 0.5 mm thick 1100 series aluminumbonded to 0.1 mm 99% pure copper with a selected material, such asScotch brand adhesive 924. The entire second layer, however, may have athickness of about 0.01 inches (in) to about 0.05 in, including about0.02 in (about 0.5 millimeters (mm)). The sheets 304, 308 will generallyhave a parameter that is generally coextensive with edges of the slottedmember 300.

The slotted member 300 may include dimensions, as discussed furtherherein. The slotted member 300 may be formed of a selected material suchas tungsten carbide having a selected amount of tungsten, such as about90% minimum tungsten. In various embodiments, the tungsten carbide isANSI grade C2 tungsten carbide. For example, the tungsten carbide may beTECHMET grade TMK-22 tungsten carbide having a about 94% tungstencarbide and 6% cobalt. In various embodiments, the grain size of the ofthe tungsten carbide component may be on the order or microns orsub-micron in size, for example about 0.5 micrometers to about 2micrometers, and including about 1.0 micrometers to about 1.4micrometers, and further including about 1.2 micrometers. The slottedmember 300 further includes a selected number of slots or slits that areformed through the slotted member 300, such as a first slot 340, asecond or middle slot 344, and a third slot 348. The slots 340, 344, 348may be used to form selected x-ray beams, volumes, or areas, such asfans, when positioned over the aperture 232 of the stage 228. Asdiscussed above, and further herein, the slotted filter 260 may be usedto generate or form a beam of x-rays relative to the subject 28 forcollecting image data thereof.

Generally, the slotted filter 260 may be positioned such that the firstsheet 304 is positioned away from the subject 28 and generally near thesource of the x-rays (e.g. the x-ray tube 190). Accordingly, the x-raysmay generally pass through the slotted filter member assembly 260generally in the direction of the vector or arrow 94 first engaging thefirst layer member 304 and finally engaging or passing through thesecond layer sheet 308. Generally, the slotted member 300 will block allor substantially all of the x-rays that pass through the first sheet 304save for the x-rays that pass through the slots 340, 344, 348.Accordingly, x-rays that engage the detector 78 when passing through theslotted filter member 260 are limited to only those x-rays that passthrough the slots 340, 344, 348. It is understood, however, at notedabove the members 304, 308 may be placed in any appropriate mannerrelative to the slotted member 300. Further, the materials selected forthe first and second members 304, 308 may assist in refining and/orselecting spectral content of the x-rays that pass through the filterassembly 260.

The slot filter assembly 260 includes the slotted member 300, asdiscussed above. As illustrated in FIGS. 4B and 4C the slotted member300 includes various features including the slots 340, 344, 348. Theslotted filter 300 includes a main body or member 352 through which theslots 340, 344, 348 are formed. The main body 352 may have a selectedthickness 354, the thickness 354 may be about 0.01 in to about 1 in,including about 0.01 in to about 0.1 in, and further including about0.07 in to about 0.1 in and further about 0.09 in (about 2.2 mm). It isunderstood that the thickness 354 of the main body 352, either alone orin combination with the other filtered layers 304, 308, may be used toform or define the x-rays that pass through the filter assembly 260. Themain body 352 may include further dimensions for various purposes,however, these dimensions may be based upon the size of the aperture232, the size of the filter assembly 224, or other appropriateconstrictions. Nevertheless, in various embodiments, the main plate 352may include a length dimension 356 between terminal ends of about 0.5 into about 2 in, and including about 1.4 in (35 mm). A width dimension 360may be about 0.1 in to about 2 in, and further including about 0.9 in(22 mm). The main plate 352 of the slot filter member 300 may includevarious configurations, such as chamfered or angled corners 364 that mayform an angle of about 45 degrees relative to the ends of the main body352. Again, it is understood, that the filter assembly 260 may includevarious configuration for fitting in a selected imaging system, such asthe imaging system 36, and specific shapes of the exterior may be basedupon configurations of the imaging system 36. The thickness 354,however, may be selected to ensure minimal or no x-ray radiation passesthrough the filter assembly 260 other than through the slots 340, 344,348.

With continuing reference to FIG. 4A and FIG. 4B, and particularreference to FIG. 4C, the main slot filter body member 352 has athickness 354. The thickness 354 is defined by or between the twosurfaces 320 and 330. In various embodiments, the surface 320 may be asurface that is positioned closest to the source of the x-ray radiationwhile the second surface 330 is the surface positioned closest to thesubject 28. It is understood that the surfaces may also be referred to,respectively, as the top surface 320 and the bottom surface 330. It isunderstood, however, that top and bottom are merely exemplary and notintended to define an absolute position of the filter body member 352.

The filter body member 352 including the three slots includes the middleslot 344 and two edge slots 340, 348. Each of the slots are formed tobetween and through the two sides 320, 330, as discussed further herein.Each of the three slots may be formed through the member 352 in anappropriate manner, such as electrical-discharge machining or otherappropriate tool (e.g. a router or punch). It is further understood thatthe slots may be forged or otherwise cut into the member 352.Nevertheless, near or at the first surface 320 each of the three slots340, 344, 348 are formed by two respective side walls each, for examplethe first slot 340 is formed between the side walls 370 and 374; thesecond slot 344 is formed between the side walls 378, 382; and the thirdslot 348 is formed between the side walls 386 and 390. It is understood,as illustrated in FIG. 4C, that the side walls extend between two ends357 and 358 of the member 352. The side walls for each of the slots 340,344, 348 are generally equal distances apart and substantially parallelalong the length of the respective slots. Further, the slot walls aregenerally straight and parallel relative to one another. It isunderstood, however, that certain tooling cause various portions of theslots to be of a slightly different dimension, such as an entry or exitplunge cut to initiate or end the slot. However, each of the slots 340,344, 348 are generally formed to have a dimension 398 of about 0.001 into about 0.1 in, including about 0.009 in to about 0.03 in, and furtherincluding about 0.025 in to about 0.01 in, and further including about0.02 in (about 0.5 mm). The width 398 of the slots 340, 344, 348 may besubstantially identical for each of the slots is generally a dimensionbetween the interior surfaces of the respective opposed walls of therespective slots.

The respective walls forming the respective slots at the first surface320 may each have a center between the respective walls. For example theslot 340 may have a center line or axis 400, the second slot 344 has acenter axis 404 and the third slot 348 has a center axis 408. Each ofthe axes 400, 404, 408 may be of a point that is at a center between therespective walls and substantially perpendicular to the surface 320. Thecenter points or axes 400, 404, 408 are generally or substantiallyperpendicular the surfaces 320, 330 and may be spaced a selecteddistance apart such as a distance 412. The distance 412 may be the samebetween each of the slots and may be about 0.01 in to about 1 in, andfurther about 0.1 in to about 4 in, and further about 0.318 in to about0.322 in (8.0 mm to about 8.2 mm) apart. The distance 412 may beselected based upon various parameters, such as the size of the slotmember 352, the size of the aperture 232 in the filter stage 228, orother appropriate considerations. Accordingly, the distance 412 may beselected based upon various parameters. It is understood, however, thatthe spacing 412 between the respective slots 340, 344, 348 may be asubstantially precisely selected for various imaging gatheringtechniques and/or stitching, as discussed further herein.

The respective central axes 400, 404, 408, as discussed above, aredefined or may be defined by a point that is at a center between therespective walls at the first side 320 and substantially orthogonal tothe first side 320. The central or second slot 344 may have the sidewalls 378, 382 that are substantially parallel with the central axis 404and substantially perpendicular to the surface 320. Accordingly, thecentral axis 404 may extend through the plate member 352 substantiallyparallel with the side walls 378, 382. The distance or width 398,therefore, may be substantially split in half or divided by the centralaxis 404.

The edge slots 340 and 348, however, may have respective central axes420 and 424 that extend substantially parallel to the respective sidewalls 370, 374 and 386, 390 and not perpendicular to the surface 320.The central axes 420, 424 may form an angle relative to the respectivecenter point axis 400, 408. For example, the first slot 340 having thecentral axis 420 may form an angle 428 relative to the center point axis400. The angle 428 may be about 5 degrees to about 10 degrees andfurther about 6 degrees to about 8 degrees, and further about 7 degrees.The central axis 424 may also form an angle 432 relative to the centerpoint axis 408. The angle 432 may be about 5 degrees to about 10degrees, and further about 6 degrees to about 8 degrees, and furtherabout 7 degrees. Accordingly, the angles 428, 432 may be substantiallysimilar or identical as an internal angle between the respective centralaxes 420, 424 and the center point axes 400, 408. The angles 428, 432may also be formed relative to either of the surfaces 320, 330 as thecenter point axes are substantially perpendicular to both surfaces 320,330.

The angles 428, 432 may assist in allowing x-rays to pass from thesource 190, as schematically illustrated in FIG. 4C, through therespective slots 340, 344, 348 without any or substantial distortion dueto interaction with the respective side walls 370, 374, 379, 382, 386,390. As illustrated in FIG. 4C and as discussed above, the x-rays may beemitted from the source tube 190 in substantially a cone shape.Accordingly, x-rays that travel substantially normal to the surface 320will pass through the central slot 344 along the central axis 404without substantial or any interaction with the side walls 378, 382.Also due to the respective angles 428, 432, the x-rays that are near anedge of the cone 90 may pass through the edge slots 340, 348 withoutsubstantial interaction with the respective side walls 370, 374, 386,390 due to the respective angles 428, 432.

The slot filter member 300 of the slot filter assembly 260, according tovarious embodiments, may allow for a formation of three x-ray fans orareas of x-rays including a first fan 440, a second fan 444, and a thirdfan 448 due to the respective slots 340, 344, 348. The three fans areformed by the slot filter 260, including the main member 300, filterx-rays from the source 190 save for the area of the slots 340, 344, 348.In other words, the slot filter 260 filters the x-rays from the source190 and allows the x-rays to pass through the slots 340, 344, 348 toform the fans 440, 444, 448. In various embodiments, the slot filterassembly 260, such as the main body 300, is a distance 450 from thesource 190. The distance 450 may be about 50 mm to about 100 mm,including about 60 mm to about 80 mm, further including about 68 mm toabout 72 mm.

As discussed further herein, the three fans 440, 444, 448 allow forgeneration of selected image projections due to an imaging area on thedetector 78. Further, due to the angles 428, 432, as discussed above,the first and third fans 440, 448 are not substantially distorted due tointeraction of x-rays with the plate member 352. It is furtherunderstood that the numbering of the slots 340, 344, 348 and therespective fans 440, 444, 448 is merely for clarity of the currentdiscussion, and not intended to require any particular order. Further,it is understood, that the filter member 352 may include a selectednumber of slots, such as less than three or more than three and three isillustrated and discussed for the current disclosure. It is understood,however, that the three slots 340, 344, 348 allow for the generation ofa long view in an efficient and fast manner, as discussed furtherherein. Including a selected different number of slots may allow for ageneration of a different number of intermediate images as discussedherein, but is not required.

As discussed above, the slot filter assembly 260 may be used in theimaging system 36 to acquire images of the subject 28. Returningreference to FIG. 2, the SDU 98 may be moved around the subject 28within the gantry 70. It is understood that the SDU 98 may be moved inany appropriate manner, and that the imaging system 36 is exemplary.Nevertheless, in various embodiments, the SDU may be rotated from afirst position to a second position, such as about 90 degrees apart. Forexample, as illustrated in FIG. 2, a first position of the SDU 98 mayinclude the source 74 directing the x-rays along the cone 90 for thedetector 78 which may be generally an anterior to posterior (AN)orientation relative to the subject 28. The SDU 90 may be rotated 90degrees, such that the source is at a second source position 74′ and thedetector may be moved to a different position such as at a seconddetector position 78′. The SDU 98 may be positioned at either or both ofthe positions and a line scan of the subject 78 may be formed.

The line scan may include moving the gantry 70, including the SDU 98,along the long axis 106 of the subject 28 which may also be referred toas a Z axis or Z direction of the imaging system 36 generally in thedirection of the double headed arrow 114, as illustrated in FIG. 1. Thedetector 78 may, therefore, be moved in a linear direction substantiallywith movement only in the direction of the double headed arrow 114 alonga Z axis. The acquired image data may be used to form a long film orlong view of the subject 28 with the image data acquired at one or bothof the positions of the detector 78, 78′ as illustrated in FIG. 2. Theuse of a slot filter 260 may be used to generate a plurality of viewsalong the Z axis, as discussed further herein.

As illustrated in FIG. 4C and with further reference to FIG. 5A and FIG.5B, the slot filter assembly 260 may be used to form the three fans 440,444, 448 that reach or have attenuations that are detected by thedetector 78. Each of the fans 440, 444, 448 directly or haveattenuations that impinge or contact the detector 78 at a substantiallynarrow position or area. As illustrated in FIG. 5B, the detector 78 mayinclude a plurality of excitable or detector regions or portions 460.The detector regions 460 may also be referred to as pixels and mayrelate to a single picture element (pixel) that is illustrated on thedisplay 44 in the image 40.

The entire cone 90 from the source 74 may have an area that would exciteor impinge upon the entire surface of the detector 78. However, theindividual fans 440, 444, 448 generally impinge upon only a narrow bandof the pixels 460. It is understood that the number of pixels excitedmay include an entire width 464 of the detector 78, but limited to onlya selected length 468 of the detector. For example, the respective fans440, 444, 448 may impinge upon, assuming that no object or subject iswithin the path of the x-rays (e.g. an air scan), about 10 about 100pixels. The number of pixels excited in the dimension 468 on thedetector 78, however, may be augmented or adjusted depending upon thedistance from the detector 78 of the filter assembly 260, the width ofthe slots (340, 344, 348), or other appropriate considerations.Nevertheless, as illustrated in FIG. 5A and FIG. 5B, each of therespective fans 440, 444, 448 will impinge upon the detector 78 at asubstantially narrow position and excite a length 468 of pixels that maybe along a substantially entire width 464 of the detector 78. The widthof the slots 398 that causes the length of pixels 468 to be excited(e.g. generate image data) limits or eliminates parallax distortionwithin the image portion collected with the imaging system using theslot filter 300, as discussed herein.

Further, as illustrated in FIG. 5A and FIG. 5B, the detector 78 may beimpinged upon by the three fans 440, 444, 448 substantiallysimultaneously from a single position of the source tube 190 along the Zaxis generally in the direction of the double headed arrow 114. Thedetector 78, therefore, may output three different images or image datafor three different positions of the x-ray at each single position ofthe source tube 190. Movement, of the source tube 190 of the source 74generally in the direction of the double headed arrow 114, however, maycreate a plurality of three views along the Z axis, as discussed furtherherein. Each of the fans 440, 444, 448 may be separated by a selecteddistance, which may also be an angular distance 472.

The imaging system 36 may be used to generate images of the subject 28,for various purposes. As discussed above, the images may be generated ofthe subject 28 for performing a procedure on the subject 28, such as aspinal fusion and/or implants relative to or adjunct to a spinal fusion.In various embodiments, therefore, user 24 may evaluate the subject 28by viewing and evaluating images of the subject 28 for determination ofplacement of selected implants, such as pedicle screws. Accordingly, theimaging system 36 may be used to acquire an image of the subject 28. Theimage system 36 may be used to acquire one or a plurality ofprojections. As further discussed above, the detector 78 detects x-raysthat pass through or are attenuated by the subject 28. Generally,however, the detector 78 detects a single projection at a time. Theimaging system 36, including the control system 64, either alone or incombination with the processor system 48 may generate a long film orlong view of the subject 28 by accumulating (e.g. stitching) a pluralityof projections of the subject 28. In various embodiments, the imagingsystem 36, therefore, may be operated to acquire a plurality of images.

Turning reference to FIG. 6, a method 500 of acquiring images, such as along view of the subject 28, is illustrated. The method 500 may includeor start in start block 510. The method 500 may then include positioningof the subject 28 in block 514. Positioning the subject 28 in block 514may include positioning the subject 28, which may be a human patient, onthe support 32 relative to the imaging system 36. Also, as discussedabove, the imaging system 36 may be a mobile imaging system, thuspositioning the subject 28 in block 514 may include moving the imagingsystem 36 relative to the subject 28. In particular, positioning thesubject 28 may include positioning the subject 28 relative to a centeror isocenter of the imaging system 36 such as within the gantry 70 andbetween the source 74 and the detector 78.

After positioning the subject 28 in block 514, acquisition parametersmay be set or input in block 518. Inputting acquisition parameters mayinclude the selected length of the view of the subject 28, theresolution required or selected, specific movement parameters of theimaging system 36, or other appropriate input parameters. For example,the user 24 may input a length or number of vertebrae to be imaged. Thecontroller 64 may then determine an amount of movement, such as a lengthin the axial direction along the long axis 106 of the patient and thedirection of the double headed arrow 114. Further, the user 24 mayselect to acquire image data that may be reconstructed into athree-dimensional model, as discussed herein. Accordingly the user 24,either manually or automatically with the control system 64, or otherappropriate control or processor system, may determine acquiring imagesof the subject 28 along at least the AP view and a lateral view to allowfor reconstruction of a three-dimensional model. It may further beunderstood that only a selected two-dimensional view may be acquired orselected of the subject 28 and therefore only a single line scan may beacquired. It is further understood that the imaging system 36 may beused to acquire any appropriate type of image of the subject 28 and thata line scan for long view is merely exemplary. Nevertheless, a line scanmay be acquired of the subject 28 by moving the SDU 98 in a generallylinear manner or direction from a start point to an end point. Invarious embodiments, an AP view may be collected in a first directionalong the arrow 114 and the SDU 98 may be rotated 90 degrees to collecta lateral view on a return path for the same length along the arrow 114.

After setting acquisition parameters in block 518, the projections ofthe subject are acquired in block 522. The acquisition of theprojections may include acquiring a slot or fan projection in a linescan of the subject 28. The acquisition of the projections may includeacquiring the three fan projections at a plurality of locations of thesource and detector and the SDU 98 along the line path, such as alongthe longitudinal axis 106 of the subject 28. The number of acquisitionsmay be selected based upon the quality desired or selected for the finallong view, including insuring an appropriate focus, minimizing oreliminating distortions (e.g. edge distortions), or other appropriateconsiderations.

After the acquisition of the projections in block 522, a reconstructionof a long view also referred to as a long film, is made in block 526.The reconstruction of the long view may include various sub-steps andsub-algorithms, as discussed further herein, to form a selectedreconstruction, such as long view of the subject 28. The reconstructionmay include various features such as ensuring an appropriate focus,iterating the plurality of projections, or the like. The plurality ofprojections may then be stitched together into a long view, eithersequentially or to provide a plurality of long views, as discussedherein.

The long view may then be optionally saved in block 530. Saving the longview in block 530 may be saving the long view in any appropriate memory,such as the imaging system memory 68 and/or the processing system memory58. It is understood that saving the long view is optional and is notrequired. The long view may then be displayed on a selected displaydevice in block 534, such as on the display device 44. The image 40 mayinclude the long view reconstructed in block 536 or include only thelong view reconstructed in block 526. The displaying of the image inblock 534, however, may also be used to illustrate the position of theinstrument 144, such as with the instrument icon or representation 180that is discussed above.

The procedure 500 may then end in end block 540. Ending in block 540 mayinclude stopping operation of the imaging system 36 and allowing aprocedure to continue, as discussed above. In various embodiments, theacquisition of the long view may be used for planning a procedure on thesubject 28, such as prior to a procedure or in an operating room madeduring an intermediate step of the procedure. Further the long view maybe acquired for various purposes, such as conformation of a step of theprocedure (e.g. placement of a first pedicle screw or other appropriatenumber of pedicle screws), or other steps. Accordingly, ending in block540 may be ending the acquisition of projections and reconstruction of along view for display and use by the user 24, or other appropriate user.

With continuing reference to FIGS. 1-6, and additional reference to FIG.7 the reconstruction of the long view in block 526, illustrated in FIG.6, may include various sub-steps and/or sub-portions as illustrated inFIG. 7. Accordingly, FIG. 7 illustrate details of the reconstruction ofthe long view in block 526 and may be incorporated into the method 500,discussed above. The method 500, therefore, may include the sub-portionsas illustrated in FIG. 7.

With continuing reference to FIG. 7, the reconstruction of the long view(also referred to herein as reconstructed long view) generally includesthe portions or sub-portions, as illustrated in block 526. It isunderstood that various features and steps may be included asinstructions, such as with an algorithm, that are executed by one ormore processor or processor systems. For example, the imaging systemprocessor 66 and/or the processing system 48 having a processor 56, mayexecute instructions to generate the long view based upon the pluralityof acquired projections from block 522. As discussed above, operation ofthe imaging system 36 may acquire the plurality of projections in block522, such as with the slot filter assembly 260. Accordingly, the imagingsystem 36 may generate projections that are based upon x-rays detectedby the detector 78. Inputting the acquired projections in block 550 mayinitiate the reconstruction process 526, as discussed above and herein,the input of projections from three slots is exemplary and more or lessis possible.

The x-ray projections may be acquired at the detector 78 with each ofthe three slots that generate the respective fans 440, 444, 448. Withcontinuing reference to FIG. 7, and additional reference to FIG. 8 eachof the three fans 440, 444, and 448 will generate three separate seriesof images or projections 560, 564, 568, respectively. Each of the seriesof projections includes a plurality of projections that are acquiredsubstantially simultaneously. For example, the first series 560 mayinclude a first image slice 560 i that will be acquired at the sameposition of the SDU 98 as a first image 564 i and 568 i of each of therespective fans 440, 444, 448. As the SDU 98 moves in the selecteddirection, such as along the axis 106 in the direction of the arrow 114,a plurality of projections are acquired through each of the slots due toeach of the fans 440, 444, 448. Accordingly, three series 560, 564, 568of projections are acquired due to movement of the imaging system 36along a selected line scan. These series of projections 560, 564, 568are the input projections in block 550 from each of the three slots. Asdiscussed further herein, although each of the slots and the respectivefans 440, 444, 448 are used to generate respective series of projections560, 564, 568, all of the image projections may be used to generate thelong view that is reconstructed in block 526. Accordingly, the input ofthe x-ray projections from all three slots in 550 may include input ofall three series of projections 560, 564, 568 which may be analyzed orevaluated separately, in various portions of the reconstruction of 526,and then combined to form the final long view, as discussed furtherherein. Each of the image slices for each of the series (e.g. 560 i, 564i, and 569 i) generally and/or substantially are free of parallaxdistortion due at least in part to the width of the slot 398 and thecorresponding length 468 excited on the detector. Thus, the slices maybe clearer and have less error or distortion due to the slice width 398.

The procedure 526, further includes an input of a motion profile of theimaging system 36 in block 578. The input of the motion profile of theimaging system in block 578 may include the distance traveled, time ofdistance traveled, distance between acquisition of projections, andother motion information regarding the imaging system 36. The motionprofile information may be used to determine and evaluate the relativepositions of the projections for reconstruction, as discussed herein.

After the input of the x-ray projections from block 550, a plane offocus may be set, such as arbitrarily, at a selected axis or line suchas focus plane (fp)=0 in block 590. A fp=0 may be defined as theisocenter of the imaging system 36. With continuing reference to FIG. 7and FIG. 8, the fp may be defined relative to a portion being imaged,such as a spine 28 s of the subject 28. The FP=0 may be an arbitraryposition and used to stitch together or put together the series ofprojections into selected intermediate images for each slot in block600.

The generation of the intermediate images at the selected FP maygenerate the intermediate images for each of the series 560, 564, 568,as illustrated in FIG. 8. Accordingly, a first intermediate image 610may be generated based upon the first series of projections 560. Asecond intermediate image 614 may be based upon the series ofprojections 564 and a third intermediate image 618 may be based upon thethird series of projections 568. Each of the intermediate images 610,614, 618 may be stitched together using generally known techniques suchas image blending, registration, and view manipulations. These mayinclude blending various portions of images that are near matches (e.g.determined to be similar portions) to achieve continuity. Registrationincludes matching or identifying identical portions of two or moreimages. Manipulations allow for altering different images or portionsthereof, as discussed herein.

The plurality of projections, also referred to as image data portions,in each of the series, such as the first series 560, are taken at aselected rate as the SDU 98 moves relative to the subject 28. Asillustrated in FIG. 8, the subject 28 may include the spine 28 s. As theSDU 98 moves, for example, the fan 440 is moved a selected distance,such as 1 centimeters (cm) per projection acquisition. Accordingly, eachof the image projections, such as the image projection 560 i, may be thewidth on the detector of the fan 440 and a second image projection 560ii may be 1 cm from the first image projection 560 i and also the widthof the fan 440 on the detector 78. A selected amount of overlap mayoccur between the two image projections 560 i and 560 ii that allows forstitching together into the intermediate projection or image 610, as isgenerally known in the art. Each of the series of projections 560, 564,568 (which may each include image data portions), therefore, may bestitched together at the respective focus plane to generate theintermediate images 610, 614, 618. As discussed above, the focus planemay be initially set at 0 or arbitrarily set at 0 which is generally theisocenter of the imaging system 36 that acquired the plurality ofprojections 560, 564, 568.

After the intermediate images are generated at the FP=0 for each slot inblock 600, a registration of the intermediate images for each slot anddetermine a translation d occurs in block 680. With continuing referenceto FIG. 7 and additional reference to FIG. 9A and FIG. 9B, theintermediate images are generated based upon the plurality ofprojections due to movement of the SDU 98. As illustrated in FIG. 9A, aschematic representation of a first movement or distance d1 isillustrated. d1 may be the d, discussed above. d1 is the distance thatthe source 74 may move from a first position 74 i to a second position74 ii. The slot filter 260 may also, therefore, move from a firstposition 260 i to a second position 260 ii. As illustrated in FIG. 9A,the second fan 444 at the first position of the slot filter 260 i andthe first fan 440 at the second position of the slot filter 260 ii mayintersect or cross at a focus plane FP=1.

As illustrated in FIG. 9B, the source 74 may move from the secondposition 74 ii to a third position 74 iii and respectively the slotfilter may move from the second position 260 ii to a third position 260iii. In this movement, a distance d2 may occur. The movement illustratedin FIG. 9B may include the middle or second fan 444 and the first fan440 intersect at a second focus plane FP=2. It is also understood thateach of the other respective fans may also intersect at differentpositions, and the illustration of the two fans are merely exemplary anddiscussion of the other fans will not be repeated, but is understood byone skilled in the art.

The position of an intersection of the fans (i.e. a distance from thesource tube 190) at the point being imaged may depend upon the positionof the object being imaged, such as the spine 28 s, from the source tube190. It is understood by one skilled in the art, the spine 28 s may notbe a straight line or extend along a straight line that is substantiallyparallel to the long axis 106 of the subject 28, even if an isocenter ofthe imaging system 36 moves along the axis 106. Accordingly, the focusplane FP may move between different positions of the source 74 and theslot filter 260, as illustrated in FIG. 9A and FIG. 9B. Thus, the firstdistance d1 which may be different from the distance d2 and may alsoalter the focus plane of the image or projections acquired with theimaging system 36. Nevertheless, the first intermediate image generatedin block 600 may assume that the focus plane is at the isocenter of theimaging system 36.

With continuing reference to FIG. 9A and additional reference to FIG.9B, the first intermediate image 610 and the second intermediate image614 are displayed. The intermediate images may include all of theintermediate images, including the intermediate images 610, 614, 618 andthe discussion of only the first intermediate image 610 and the secondintermediate image 614 is merely for clarity of the current discussion.Nevertheless, the intermediate images 610 and 614 may be registered toone another to determine or generate a registered image 640.

The registered image 640 may include a first end 644 that is equal to afirst end 648 of the first intermediate image 610 and a second end 654that is equivalent to a second end 660 of the second intermediate image614. Accordingly, the registered image 640 may be a composite or overlayof the first intermediate image 610 and the second intermediate image614. In particular, an area of overlap 664 may be determined oridentified between the first intermediate image 610 and the secondintermediate image 614. The overlap 664 may be identified such asthrough feature based registration, mutual information basedregistration, or other appropriate registration or image matchingmethods.

As illustrated in FIG. 9B, the second intermediate image 614 has thesecond end 660 that is a distance 668 from a second end 670 of the firstintermediate image 610. The distance 668 may be used or be identified asthe distance d of movement of the imaging system and may be used toalter or determine a plane of focus for each of the intermediate images,or a mutual plane of focus for the intermediate images. Accordingly, dueto the registration image 640 that is determined by registering thefirst intermediate image 610 and the second intermediate image 614 thedistance d may be determined in block 680.

After determining the distance d, which may be a translation distanceand is related to the slot filter spacing (e.g. distance 412), focusplane and region of interest in the subject to be imaged (e.g.anatomical region of interest such as a specific vertebrae or spinousprocess of a vertebrae), in block 680, an updated plane of focus FPincluding the distance d may be made in block 684. The distance d, asillustrated in FIG. 9B, may relate to a distance of an adjustment ofdistance to achieve an alignment of registered elements (e.g. a spinousprocess) between two or more intermediate images, such as image 610 and614 to generate the registered image 640. Also, the distance betweenslots, such as the distance 412, may be used to determine thetranslation distance d to achieve the registered image 640. The imageportions acquired through different slots, even at the same location ofthe slot filter 260, are at different positions along the subject.

The updated FP, based on the analysis discussed above, including theposition of the portion of interest within the subject (e.g. anatomy ofinterest), may then be input or iterated to generate updatedintermediate images with the updated FP in block 690. The updated FP forthe iteration to generate the updated image may account for a positionof the subject or region of interest from the source 74 between twodifferent intermediate images (e.g. image portions). The generation ofthe updated intermediate images may be substantially similar to thegeneration of the intermediate images in block 600, except that thefocus plane has been updated based upon the determined translation d.Thus the focus of the intermediate images may be increased or refineddue to a determination of the focus plane in light of the translation ofthe images, as determined above as illustrated in FIG. 9B. The generatedupdated images in block 690 may then be combined in the combining ofintermediate images with a weighting function in block 700. As discussedabove and herein, including three intermediate images based on threeslots is merely exemplary, and more or less may be allowed or used.

Prior to the generation of the combining in block 700, however, adetermination of whether further updated intermediate images may be madein block 692. For example, at least two iterations may occur todetermine if a selected minimum is reached. If a minimum is not reached,a further iteration may occur. Regardless of the determination, adecision of whether a further update of the fp may be made in block 692.If an update is made, a YES path 694 may be followed and the fp placemay be updated in block 684 and the process may iterate. If no furtherupdate is needed or selected, a NO path 696 may be followed to combinethe three intermediate images in block 700.

With continuing reference to FIG. 7 and additional reference to FIG. 10,the intermediate images that are updated in block 690 may include thefirst updated intermediate image 610 u, a second updated intermediateimage 614 u, and a third updated intermediate image 618 u. As discussedabove, each of the three intermediate images 610 u, 614 u, and 618 u maythen be combined to generate a first or initial long view or long filmimage 704.

The generation or merging of the various intermediate images, such aseach of the three intermediate images 610 u, 614 u, and 618 u, mayinclude various steps and features. In various embodiments, an initialdeformation of various features may be made when generating each of thethree intermediate images 610 u, 614 u, and 618 u. As noted above, eachof the three intermediate images 610 u, 614 u, and 618 u may begenerated based on a plurality of projections. Thus, each of the threeintermediate images 610 u, 614 u, and 618 u may include a similar orsame feature (e.g. vertebrae). The amount of deformation to generateeach of the three intermediate images 610 u, 614 u, and 618 u may bedetermined and used in further merging procedures.

According to various embodiments, a weighting function 710 may be usedto assist in the combining of the updated intermediate images 610 u, 614u, and 618 u to generate the initial long view image 704. The weightingfunction 710 is graphically illustrated in FIG. 10. A first weightingfunction for the first fan 440 w illustrates that pixels or imageportions may be weighted more for the left most portion of the long viewdue to the position of the fan 440. The intermediate or central fan 444may have the function 444 w that will weight the pixels for the middleof the long view 704 more from the updated image 614 u due to theposition of the fan 444. Finally, the fan 448 may have the function 448w to weight the pixels furthest to the right or at the end due to theposition of the fan 448 in the long view 704. It is understood thatother appropriate stitching functions may be used to generate theinitial long view 704 and that the weighting function 710 is merelyexemplary. Further, a greater weight may be given to the selectedintermediate image 610 u, 614 u, and 618 u that has the leastdeformation when generating the long view. Further, selecteddeformations, such as geometric deformations, may be made whengenerating the long view.

In various embodiments, the initial long view 704 may be output as thelong view or a long view in block 720. The long view output in block 720may be saved, such as saving the long view in block 530 and/or displayedin block 532, as discussed above in the process 500 illustrated in FIG.6. In various embodiments, however, various normalizations and/orprocessing may be applied to the initial long view 704 prior to theoutput of the long view in block 720 such as for image enhancementand/or clarity.

With continuing reference to FIG. 7, various procedures may be performedprior to the output of the final 2D long film or long view image inblock 720. After the combination of the three intermediate images withthe weighting functions, various processing steps may be performed priorto displaying and/or saving the long view image. For example, applyingan air normalization in block 730 and/or further post processing forvisualization in block 740.

The air normalization may account for or minimize effects of the slotfilter assembly 260. As illustrated in FIG. 5A and FIG. 5B the fan, forexample the fan 448, contacts or impinges upon the detector 78 in thelength distance 468. The distance 468 is a small portion of the detector78. Further, due to the narrow dimension of the fan 448 and, therefore,the small number of pixels contacted on the detector 78, an image orpixel intensity may drop off quickly, such as in a gaussian fashion asillustrated in FIG. 11, from a peak intensity pixel or point 744.

The peak intensity 744 may be at a center of the fan 448, such as thecenter of the distance 468 at a pixel or point on the detector 78.Within five pixels from the center pixel (i.e. a width of 10 pixels,including the peak intensity pixel) an intensity drop off of about 25%(e.g. the 6th pixel away may have an intensity of about 75% of the peakintensity pixel 744) may be observed in the pixels outside of the 10pixels centered on the pixel with the peak intensity 744. Within 10pixels from the center pixel (i.e. a width of 20 pixels, including thepeak intensity pixel) an intensity drop off of about 66% is observed(e.g. the 11th pixel away may have an intensity of about 33% of the peakintensity pixel 744). Accordingly, a narrow band of pixels may includeall or substantially all of the intensity due to the fan 448. It isunderstood, that each of the other fans 440, 444 may include or have thesimilar pixel intensity drop off.

A mask may be applied to assist in reduce the effect of the intensitydrop-off. A mask that is 40 pixels wide may be applied to each imageacquired with each of the slots to account for and eliminate thosepixels that has substantially no intensity due to the narrow fan widths440, 444, 448. The images that are acquired are thereby normalized in areconstruction, such as due to the combination of the intermediateimages in block 700, to reduce or eliminate the distortion that mayotherwise be observed. For example, upon stitching a plurality of narrowimages, such as the image 460 i with the image 460 ii if thenormalization does not occur, the edges of the image may besubstantially light or have nearly no pixel intensity relative to centerpixels. Without the mask and normalization. when stitched or combined,the combined image may have a “ripple effect” that may be viewed in astitched image. The ripple effect may alternate between dark and lightbands due to the changing pixel intensity over a plurality of stitchedimages where the amount of pixel intensity drop off is substantial overa narrow ban or width of pixels.

Further post processing for visualization may occur in block 740.Various post processing can include any appropriate post processing toassist in visualization of the combined image from block 700. In variousembodiments for example, a normalization or histogram averaging (e.g. ofpixel intensities) of the image may occur. For example, the finalreconstruction may have the stitched pixel values divided by acumulative pixel value to assist in reducing or minimizing greatvariations between high contrast and low contrast areas in the combinedimage from block 700. Thus the image may be prepared for viewing withfurther post processing in block 740. The post-processing can include,but is not limited to, enhancing of anatomical features, highlightinganatomical features (e.g. masking), sharpening edges, etc.

Accordingly, in light of the above, the imaging system 36 may be used toacquire a plurality of projections of the subject 28. The plurality ofthe projections of the subject 28 may be acquired in a linear manner,such as in a first line scan in an AP (anterior to posterior) directionand a second line scan in a lateral direction. The plurality ofprojections may then be stitched or combined into a single long view orlong film view of the subject 28. Various intermediate steps, such asthose discussed above, may be performed to assist in performing orgenerating the single long view. For example, a plurality of slots in afilter may be used to generate a plurality of intermediate images thatare then finally stitched together to form the single long view.Nevertheless, the imaging system 36 may be used to generate a long viewof the subject 28.

Further each of the slots in the slot filter 260 may allow for theacquisition of a different “view” of the subject 28 during scanning ofthe subject 28. For example, each of the three fans 440, 444, 448acquire a projection at a single position of the SUD 98. Accordingly, ateach view the perspective of the subject 28 may be different. Accordingto various known techniques, therefore, a three-dimensional model of thesubject 28 may be reconstructed using the plurality of views of thesubject 28 acquired even during the line scans of the subject. A linescan of the subject, as discussed above, may be a substantially linearmovement, such as generally parallel with the long axis 106 of thesubject 28. Thus the SDU 98 may not rotate around the subject 28 duringthe acquisition of the linear scan. Nevertheless, the plurality ofprojections from the various perspectives may be used to reconstruct athree-dimensional model of the subject 28 using the single or two linescans (e.g. AP and lateral line scans). These plurality of projectionsfrom various perspectives may also be used to localize items or featuresin high-contrast objects, such as bony anatomy or implants. Thelocalized position from each of the more than one slot projections mayalso be used to generated a three-dimensional model of the subject thatis imaged. The different position in the plane determined in each of theprojections may be used to generate the 3D model, as ius understood inthe art.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

It should be understood that various aspects disclosed herein may becombined in different combinations than the combinations specificallypresented in the description and accompanying drawings. It should alsobe understood that, depending on the example, certain acts or events ofany of the processes or methods described herein may be performed in adifferent sequence, may be added, merged, or left out altogether (e.g.,all described acts or events may not be necessary to carry out thetechniques). In addition, while certain aspects of this disclosure aredescribed as being performed by a single module or unit for purposes ofclarity, it should be understood that the techniques of this disclosuremay be performed by a combination of units or modules associated with,for example, a medical device.

In one or more examples, the described techniques may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored as one or more instructions orcode on a computer-readable medium and executed by a hardware-basedprocessing unit. Computer-readable media may include non-transitorycomputer-readable media, which corresponds to a tangible medium such asdata storage media (e.g., RAM, ROM, EEPROM, flash memory, or any othermedium that can be used to store desired program code in the form ofinstructions or data structures and that can be accessed by a computer).

Instructions may be executed by one or more processors, such as one ormore digital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor” as used herein may refer toany of the foregoing structure or any other physical structure suitablefor implementation of the described techniques. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

What is claimed is:
 1. A system including a filter assembly, comprising:a main member having a first surface and a second surface, wherein atleast a first slot and a second slot are formed through the main memberand the first surface and the second surface; a first covering memberhaving a first surface and an opposed second surface, wherein the firstsurface is substantially co-extensive with the main member first surfaceand fixed relative to the main member; wherein the main member is formedof a x-ray blocking material; wherein the first slot is defined betweena first internal surface and a second internal surface formed in themain member; wherein a first distance between the first internal surfaceand the second internal surface is about 0.01 mm to about 6 mm; whereinthe second slot is defined between a third internal surface and a fourthinternal surface formed in the main member; wherein a second distancebetween the third internal surface and the fourth internal surface isabout 0.01 mm to about 6 mm.
 2. The system of claim 1, wherein the mainmember further comprises a third slot; wherein the third slot is definedbetween a fifth internal surface and a sixth internal surface formed inthe main member; wherein a third distance between the fifth internalsurface and the sixth internal surface is about 0.01 mm to about 6 mm.3. The system of claim 2, wherein the first distance, the seconddistance, and the third distance are all about 4 mm.
 4. The system ofclaim 1, wherein the main member is formed of a tungsten carbide alloyhaving at least about 80% tungsten.
 5. The system of claim 1, whereinthe first covering member is formed of an aluminum alloy.
 6. The systemof claim 1, further comprising: a second covering member having a firstsurface and an opposed second surface, wherein the first surface issubstantially co-extensive with the main member second surface and fixedrelative to the main member; the second covering member comprising afirst portion and a second portion, wherein the first portion and thesecond portion are substantially co-extensive and the first portion isformed of an aluminum alloy and the second portion is formed of asubstantially pure copper; wherein the second portion is fixed relativeto the main member such that the second portion is exposed away from themain member.
 7. The system of claim 1, wherein the first surface of themain member is opposed to the second surface of the main member andabout 0.2 mm to about 3 mm.
 8. The system of claim 1, wherein the firstinternal surface extends substantially parallel to the second internalsurface; wherein a line between the first internal surface and thesecond internal surface extends at an angle of about 5 degrees to about10 degrees relative to the first surface.
 9. The system of claim 2,wherein the first slot and the third slot are formed through the mainmember on opposed sides of the second slot; wherein the fifth internalsurface extends substantially parallel to the sixth internal surface;wherein a first line between the first internal surface and the secondinternal surface extends at an angle of about 5 degrees to about 10degrees relative to the first surface.
 10. The system of claim 9,wherein the first internal surface extends substantially parallel to thesecond internal surface; wherein a second line between the firstinternal surface and the second internal surface extends at an angle ofabout 5 degrees to about 10 degrees relative to the first surface. 11.The system of claim 10, wherein the third internal surface extendssubstantially parallel to the fourth internal surface; wherein a thirdline between the third internal surface and the fourth internal surfaceextends substantially perpendicular relative to the first surface. 12.The system of claim 11, wherein the first line is spaced about 7 mm toabout 9 mm from the second line; wherein the second line is spaced about7 mm to about 9 mm from the third line.
 13. The system of claim 12,further comprising: a x-ray source; wherein the main member is spacedabout 50 mm to about 100 mm from the source; wherein the main memberforms three fans from the x-ray source relative to a detector.
 14. Thesystem of claim 1, wherein the first distance and the second distancesubstantially eliminate parallax in an image generated with image dataacquired with an x-ray source and x-ray detector spaced from the mainmember.
 15. A method of forming a system with a filter assembly,comprising: forming a first slot through a main member having a firstsurface and a second surface, wherein the first slot is formed throughthe main member and the first surface and the second surface, whereinthe first slot is defined between a first internal surface and a secondinternal surface formed in the main member and wherein a first distancebetween the first internal surface and the second internal surface isabout 0.01 mm to about 6 mm; forming a second slot through the mainmember having the first surface and the second surface, wherein thesecond slot is formed through the main member and the first surface andthe second surface, wherein the second slot is defined between a thirdinternal surface and a fourth internal surface formed in the main memberand wherein a second distance between the third internal surface and thefourth internal surface is about 0.01 mm to about 6 mm; fixing a firstcovering member to the main member, wherein the first member has a firstsurface and an opposed second surface, wherein the first surface issubstantially co-extensive with the main member first surface and fixedrelative to the main member; fixing a second covering member to the mainmember, wherein the second covering member has a third surface and anopposed fourth surface, wherein the third surface is substantiallyco-extensive with the main member second surface and fixed relative tothe main member; wherein the main member is formed of a x-ray blockingmaterial.
 16. The method of claim 15, further comprising: forming athird slot through the main member having the first surface and thesecond surface, wherein the third slot is formed through the main memberand the first surface and the second surface, wherein the third slot isdefined between a fifth internal surface and a sixth internal surfaceformed in the main member and wherein a third distance between the fifthinternal surface and the sixth internal surface is about 0.01 mm toabout 6 mm.
 17. The method of claim 16, further comprising: forming thefirst slot to be about 7 mm to about 9 mm from the second slot; formingthe third slot to be about 7 mm to about 9 mm from the second slot; andpositioning the main member about 50 mm to about 100 mm from a x-raysource. wherein the second slot is between the first slot and the thirdslot.
 18. The method of claim 16, further comprising: reducing parallaxin an image detected at a x-ray detector by allowing x-rays to thedetector only through the first slot and the second slot and the thirdslot.
 19. The method of claim 16, wherein forming the first slot throughthe main member further comprises forming the slot at a first anglerelative to the first surface; wherein forming the third slot throughthe main member further comprises forming the slot at a second anglerelative to the first surface.
 20. The method of claim 18, furthercomprising: dividing a single emitted beam of x-rays into at least afirst beam, a second beam, and a third beam with the formed first slot,formed second slot, and formed third slot; moving the x-ray detector andthe single emitted beam of x-rays along a path relative to the subjectfrom the first position to a second position; collecting a firstplurality of image data portions based on the first beam as the imagedetector is moved to a plurality of positions; collecting a secondplurality of image data portions based on the second beam as the imagedetector is moved to the plurality of positions; collecting a thirdplurality of image data portions based on the third beam as the imagedetector is moved to the plurality of positions; generating a firstintermediate image based on the collected first plurality of image dataportions; generating a second intermediate image based on the collectedsecond plurality of image data portions; and generating a thirdintermediate image based on the collected third plurality of image dataportions.
 21. A system including a filter assembly, comprising: a mainmember having a first surface and a second surface, wherein at least afirst slot, a second slot, and a third slot are formed through the mainmember and the first surface and the second surface; a first coveringmember having a first surface and an opposed second surface, wherein thefirst surface is substantially co-extensive with the main member firstsurface and fixed relative to the main member; a second covering memberhaving a first surface and an opposed second surface, wherein the firstsurface is substantially co-extensive with the main member secondsurface and fixed relative to the main member; wherein the main memberis formed of a x-ray blocking material; wherein the first slot isdefined between a first internal surface and a second internal surfaceformed in the main member; wherein a first distance between the firstinternal surface and the second internal surface is about 0.01 mm toabout 6 mm; wherein the second slot is defined between a third internalsurface and a fourth internal surface formed in the main member; whereina second distance between the third internal surface and the fourthinternal surface is about 0.01 mm to about 6 mm; wherein the third slotis defined between a fifth internal surface and a sixth internal surfaceformed in the main member; wherein a third distance between the fifthinternal surface and the sixth internal surface is about 0.01 mm toabout 6 mm.